The present invention relates to an electrical connector structure for an electronic product, and more particularly to an electrical connector structure that is surface mountable.
For electronic products that are commonly circulated in the marketplace, consumers would, aside from expecting them to achieve specific functions, particularly demand that they have various shapes and light weight. In order to have various shapes and light weight, the internal electronic components of the electronic products have to be developed in the direction of compactness, and how to connect an electrical connector and a circuit board in a compact manner is an important subject. A conventional way of connecting an electrical connector and a circuit board is to form holes in the circuit board. That is, terminals of the electrical connector pass through through holes which are formed in the circuit board, and which are fixedly connected to corresponding contacts on the circuit board distal to the electrical connector. However, in such a connecting method, the through holes in the circuit board take up a large percentage of the wiring area of the circuit board, which is undesirable. Therefore, it becomes a problem to be solved as to how an electrical connector can be connected to a circuit board without forming holes in the latter.
At present, there are available circuit boards that are not provided with through holes, and wiring is conducted on a surface of the circuit board which is proximate to the electrical connector. The corresponding contacts on the circuit board are directly connected to the terminals of the electrical connector via solder balls after heating the latter, thereby establishing electrical connections. FIG. 1 illustrates such a known connector and shows the relative relationship among an electrical connector 7, an electronic component 6 and a circuit board 8. FIG. 2 is a sectional view taken along line Axe2x80x94A of FIG. 1, and illustrates a surface 82 of the circuit board 8 that is proximate to the electrical connector 7 is provided with corresponding contacts 84. A plurality of terminals 78 of the electrical connector 7 are each disposed in respective single through holes 76 in an insulating housing 70, with the end portions 782 of the terminals 78 slightly extending past a surface 72 of the insulating housing 70. A solder ball 71 is pre-planted in the terminal end portion 782. The electrical connector 7 with the pre-planted solder balls 71 is then brought near the circuit board 8 such that the solder ball 71 attached to each terminal end portion 782 is in contact with the corresponding contact 84 on the circuit board 8. After heating, the electrical connection is established.
Further, in another known electrical connector, as disclosed in R.O.C. Patent Publication No. 383963 and as illustrated in FIG. 3, each of a plurality of through holes 76 formed in an insulating housing 70 of an electrical connector 7 has one end located proximate to a circuit board 8 and configured to have a spherically curved matching surface 762. Each of a plurality of terminals 78 has an end portion 782 with a side surface 784 that follows the spherically curved matching surface 762, and the two of which cooperatively define a receiving space for receiving a solder ball 71, with the terminal side surface 784 in contact with the solder ball 71. After heating, the terminals and the circuit board are fixedly connected to achieve electrical connection.
Still further, in the electrical connector disclosed in R.O.C. Patent Publication No. 389430 and illustrated in FIG. 4, an electrical connector has a plate-like insulating housing 70 that is provided with a plurality of through holes 76. The edges of the through holes 76 which are proximate to a circuit board 8 are configured to have respective interior, recessed surfaces 764, the profile of which matches the shape of the solder ball 71. A plurality of terminals 78 are inserted into the through holes such that end portions 782 thereof respectively and slightly project in a straight direction from the interior recessed surfaces 764 of the through holes and contact with the solder balls 71. After heating, the terminals and the circuit board are fixedly connected to thereby establish electrical connection.
The present invention provides an improved electrical connector that utilizes solder balls as a means of connection, and which results in improved retention of the connector terminals and solder balls, as well as reduced operating height of the connector.
It is therefore a general object of the present invention to provide an improved electrical connector that reduces the distance between a mounting surface of an insulating housing and a circuit board so as to reduce the overall height after assembly, thereby achieving the object of compactization of electronic products.
Another object of the present invention is to provide an electrical connector which maintains the spherical shape of solder balls before and after soldering so as to obtain good connection with terminals and good electrical conductivity after connection.
A further object of the present invention is to provide an electrical connector that enables easy positioning and confinement of the solder balls and to avoid the drawback of poor electrical conductivity after soldering, which results from displacement of the solder balls caused by non-uniform expansion and contraction of the terminals and the circuit board during the soldering and heating process due to difference in the materials of the terminals and the circuit board.
The electrical connector of the present invention mainly provides an electrical connection between an electronic component (such as a central processing unit) and a circuit board. The present invention is characterized in that a depression is formed in one lateral edge of a mounting surface of an insulating housing of the electrical connector adjacent to a through hole, and that one end of a terminal extends through an opening of the through hole, bends, and is positioned in the depression to thereby form a mounting portion for attachment of a solder ball thereto. The structure includes: an insulating housing, the insulating housing having a receiving surface for receiving an electronic component, and a mounting surface disposed to be proximate to the circuit board, a plurality of terminal through holes being disposed between the receiving surface and the mounting surface, the mounting surface being provided with depressions each of which is adjacent to an opening of a respective one of the through holes and is sunken toward the interior of the insulating housing; and a plurality of conductive terminals respectively disposed in the through holes such that when a respective one of the terminals is disposed in the respective through hole, a free end thereof extends outwardly of the opening of the respective through hole in the mounting surface and bends obliquely toward the depression so that the free end of the terminal is located in the depression to form a mounting portion and so that the solder ball is confined between the mounting portion and a side wall of the depression and can thus be positioned. The spherical shape of the solder ball and good connection can therefore be maintained. Furthermore, as the depression is sunken into the interior of the insulating housing, the distance between the circuit board and the insulating housing after soldering can be reduced to thereby reduce the height of the assembly of the circuit board and the electrical connector.
The technical means employed by the present invention in order to achieve the aforesaid objects and features, and the effects of the invention are described hereinafter by way of the preferred embodiments with reference to the accompanying drawings, in which like reference numerals identify like parts.